The invention relates to methods for optionally dispensing, receiving or storing semiconductor devices including integrated circuits and, more specifically, to methods employing vertical stacking of such devices in magazines.
As the semiconductor industry advances in the fabrication and processing of packaged semiconductor devices (sometimes referred to herein for convenience as xe2x80x9cdevicesxe2x80x9d), such as thin small outline packages, or TSOPs, testing and sorting of such devices pose challenges in terms of device throughput, test equipment space utilization, and device distribution responsive to test result-responsive sorting.
Currently, processing of thin package devices such as TSOPs is primarily carried out based upon specialized JEDEC (Joint Electronic Device Engineering Council) specification trays, which are approximately five inches wide by twelve inches long. The JEDEC tray design dictates that the semiconductor devices are carried in a single layer, arranged in mutually perpendicular rows and columns. Tray density, or the number of devices carried by each tray, obviously decreases as device size increases. For reference purposes, if a given device is 0.400 inch wide by 0.750 inch long, a JEDEC tray part capacity, with a nine row by thirteen column configuration, is about 117 parts per tray.
Testing of the devices is conventionally carried out in batches of thirty-two parts (devices) run through a test cycle simultaneously. The devices are then sorted into a number of categories based upon test results and then xe2x80x9cbinnedxe2x80x9d into the aforementioned JEDEC trays by a conventional xe2x80x9cpick-and-placexe2x80x9d robotic arm system. At the present time, as many as sixteen sort categories are employed, and it is anticipated that the number of sort categories will increase as the sophistication and miniaturization of semiconductor devices continue in the future. If each JEDEC tray employed for receiving post-test devices is intended to receive a single bin or sort category, a substantial amount of manufacturing floor space is required to accommodate an arrangement where sixteen JEDEC trays are placed in a horizontal array. Further, the size and complexity of the pick-and-place device required to place tested devices in the trays of such an array become unreasonable. Alternatively, if (for example) sixteen JEDEC trays are stacked in a holding tower in a vertical format, wherein the trays themselves are again horizontally oriented but mutually vertically superimposed, a tray retrieval and presentation mechanism is required. Further, the time to retrieve each tray from the tower, present it for pick-and-placement of a tested device, and replace the tray in the tower severely limits device throughput. As the number of sort categories increases, each of the foregoing approaches to device binning becomes ever-more unwieldy to execute.
Thus, the prior art approach to semiconductor device sorting and binning has demonstrated severe deficiencies in terms of throughput, space utilization, and complexity of required device handling equipment.
The present invention affords a simple, elegant and economical solution to the previously identified problems with device sorting and binning. By employing a vertical binning approach instead of the prior art horizontal binning approach, embodiments of the present invention offer the ability to simulate the horizontal spatial configuration or xe2x80x9cfootprintxe2x80x9d of a JEDEC tray for convenience of use with conventional, unmodified robotic pick-and-place equipment. Additional embodiments of the invention enable the binning of tested and sorted devices into an extremely high number of categories in a rapid, accurate manner and subsequent storage, transport and dispensing of the binned devices for subsequent operations.
One embodiment of the invention includes at least one elongated magazine configured for containing a plurality of semiconductor devices, including by way of example thin package devices, in a stacked configuration. The magazine is mounted substantially vertically and removably associated with an indexing element of an elevation assembly, the indexing element being movable to regulate the internal longitudinal volume of the interior of the magazine, in order to receive or present a device at a desired level proximate the top of the magazine from a stack of devices within the magazine. The indexing element may be driven by a stepper motor or other incrementally or continuously controllable drive employed in the elevation assembly to ensure presentation or receipt of the top device in the magazine at a correct, controllable vertical height for easy access by a pick-and-place system. The magazine and elevation assembly together may be said to comprise a magazine unit.
It is currently contemplated that a best mode of implementation of the invention may involve a plurality of magazine units in modular form placed in an array, each including a removable, vertically extending magazine placed in close mutual horizontal proximity and, if desired, in a pattern to simulate at least some of the rows and columns exhibited by the aforementioned JEDEC trays. Thus, each magazine is associated with an indexing element responsive to a separately controllable drive of a discrete elevation assembly for raising or lowering a stack of devices within that magazine to either present an uppermost device in a magazine stack for retrieval, or to lower an uppermost device in a stack to provide a location for placement of another device in that magazine.
Embodiments of the invention also include a method of binning devices and a method of dispensing stored devices for further handling.